1. Technical Field
The present invention relates to a silver halide emulsion and a silver halide color photographic light-sensitive material, more specifically, the present invention relates to a silver halide color photographic light-sensitive material using a dopant technique and ensuring high sensitivity, high gradation, no reciprocity failure, stable latent image and excellent aptitude for rapid processing.
2. Background Art
One of techniques of modifying a silver halide grain and thereby improving the performance of the entire silver halide color photographic light-sensitive material as desired is a technique of integrating a substance (dopant) except for a silver ion and a halide ion (doping technique). Particularly, many studies have been made on the technique of doping a transition metal ion. As generally recognized, when a transition metal ion is integrated as a dopant into a silver halide grain, this ion effectively modifies the photographic performance even if the amount of the dopant added is very small.
In order to more effectively improve the photographic properties of a silver halide emulsion, not only a technique of doping a transition metal ion but also a technique of doping a transition metal complex into a silver halide grain are known. The performance of a silver halide emulsion, which is improved by the doping of a transition metal complex into a silver halide grain, includes sensitivity (higher sensitivity), reciprocity failure (low illuminance reciprocity failure, high illuminance reciprocity failure) and gradation (higher contrast). In a high silver chloride emulsion, improvement in the high illuminance reciprocity failure is particularly important. For improving the high illuminance reciprocity failure, an iridium complex is used in many cases. Examples of the silver halide grain doped with an iridium complex are described in JP-A-1-285941, JP-A-3-118583, JP-A-4-213449, JP-A-4-278940, JP-A-5-66511, JP-A-5-313277, JP-A-6-82947, JP-A-6-235995, JP-A-7-72569, JP-A-7-72576, JP-A-11-202440 and JP-A-11-295841. The ligand of the iridium complex is most commonly a chloride ion but other than that, a fluoride ion, a bromide ion, H2, a cyanide ion, a nitrosyl and a thionitrosyl are used. Furthermore, a dopant technique using an organic compound as the ligand is disclosed in U.S. Pat. No. 5,360,712 and [IrCl5(thia)]2-(thia: thiazole) is disclosed as a dopant of improving the high illuminance reciprocity failure.
On the other hand, for obtaining a high-sensitive emulsion, many examples of an emulsion doped with a Group VIII metal complex having 6 cyanide ions as ligands are disclosed. JP-B-48-35373 (the term “JP-B” as used herein means an “examined Japanese patent publication”) discloses hexacyanoferrate(II) complexes and hexacyanoferrate(III) complexes as a dopant containing a cyanide ion. Also, many other examples of obtaining a high-sensitive emulsion by doping a hexacyanoferrate(II) complex are known and disclosed, for example, in JP-A-5-66511 and U.S. Pat. No. 5,132,203. Other than the iron complex, high-sensitive emulsions obtained by doping a cyano complex are known and JP-A-2-20853 discloses that when a complex of rhenium, ruthenium, osmium or iridium is doped into silver iodochloride, a high-sensitive emulsion is obtained. The doping technique is used also for obtaining a high-gradation emulsion and a technique of using a nitrosyl or a thionitrosyl as the ligand of a transition metal complex is disclosed in European Patents 033642, 0606895 and 0610670. At this time, ruthenium or osmium is used as the center metal. A high-contrast emulsion is effectively obtained by not only using a nitrosyl or a thionitrosyl but also using hexachlororuthenium, hexachlororhodium or hexachlororhenium and this is described in JP-A-63-184740, JP-A-1-285941, JP-A-2-20852 and JP-A-20855.
In recent years, a technique of doping a complex having an organic compound as the ligand into a silver halide grain so as to attain more enhanced performance by a sole dopant is disclosed. Many examples of using a complex having an organic compound as the ligand are disclosed in U.S. Pat. Nos. 5,360,712, 5,457,021 and 5,462,849, European Patent 0709724, JP-A-7-72569 and JP-A-8-179452 and it is stated that doping of [(NC)5Fe(m-4,4′-bipyridine)Fe(CN)5]6− gives a particularly large effect in the elevation of sensitivity. The above-described technique of doping [IrCl5(thia)]2 is one of these techniques aiming at enhancement in the performance of an emulsion by a sole dopant. Furthermore, JP-A-11-24194 discloses an emulsion which is favored with high sensitivity and improved in the reciprocity failure by doping [Fe(CO)4(P(Ph)3)]0 or [Fe(CO)3(P(Ph)2)]0, JP-A-11-102042 discloses a technique where in complexes of [M(CN)5L]3− (M: Fe2+, Ru2+ or Ir3+), [Fe(CO)4L]]0, [M′(CN)3L]− (M′; Pd2+ or Pt2+) or [IrCl5L]− type, when L is 2-mercaptobenzimidazole, 5-methyl-s-triazolo(1.5-A)pyrimidin-7-ol or 2-mercapto-1,3,4-oxadiazole, a high-sensitive emulsion is obtained, and JP-A-10-293377 discloses that an emulsion doped with [RuCl5L′]2− (L′: imidazole, benzimidazole or a derivative thereof) is remarkably increased in the contrast and the sensitivity thereof is greatly higher than that of an emulsion using a conventional dopant for obtaining high contrast with desensitization.
These dopants each effectively improves the photographic properties even when used solely, but by using a plurality of dopants at the same time, an emulsion having properties of respective dopants in combination can be obtained. An emulsion having high sensitivity and less reciprocity failure is realized by using a hexacyano complex and an iridium complex in combination as disclosed, for example, in JP-A-2-125425 [Patent Document 1], JP-A-3-132647 [Patent Document 2] and JP-A-3-188437 [Patent Document 3]. An emulsion having high contrast and excellent property in low illuminance and/or high illuminance reciprocity failure can be obtained by using a ruthenium or osmium complex having a nitrosyl as the ligand and an iridium complex in combination as described in U.S. Pat. No. 5,474,888 [Patent Document 4] and U.S. Pat. No. 5,500,335 [Patent Document 5] and JP-A-4-51233 [Patent document 6]. A technique of using a ruthenium or osmium complex having a nitrosyl as the ligand of complex and an iron or ruthenium complex having a cyanide ion as the ligand in combination for obtaining an emulsion having high sensitivity and high contrast is disclosed in U.S. Pat. No. 5,480,771 [Patent Document 7] and European Patents 0606893 [Patent Document 8], 0606894 [Patent Document 9], 0606895 [Patent Document 10] and 0610670 [Patent Document 11]. Also, an emulsion having high sensitivity, high contrast and less reciprocity failure can be obtained by using three kinds of dopants in combination. JP-A-8-314043 [Patent Document 12], JP-A-8-328182 [Patent Document 13], JP-A-8-211529 [Patent Document 14], JP-A-8-211530 [Patent Document 15] and U.S. Pat. No. 5,480,771 [Patent Document 16] disclose emulsions having high contrast, high sensitivity and less reciprocity failure, obtained by using hexacyanoruthenium(II) as a dopant for obtaining high sensitivity, pentachloronitrosyl osmium(II) as a dopant for obtaining high contrast, and hexachloroiridium(III or IV) as a dopant for improving reciprocity failure. Other examples of the emulsion using three kinds of dopants include an emulsion described in JP-A-11-282114 [Patent Document 17]. In this publication, an emulsion having high contrast and less reciprocity failure over a wide exposure illuminance is obtained by using pentachloronitrosyl osmium, hexachloroiridium and pentachloro(thiazole)iridium in combination.
JP-A-2002-202574 [Patent Document 18] discloses an example of using K2Ir(H2O)Cl5 and K2Ir(thiazole)Cl5 in combination, European Patent 1,282,004 [Patent Document 19] discloses an example of using K2Ir(thiazole)Cl5 and K2Ir(5-methyl-thiazole)Cl5 in combination, and JP-A-2002-214733 [Patent Document 20] discloses an example of using three or more transition metal complexes differing in the classified electron releasing time, in combination.
Even with these currently known techniques of enhancing the performance by each dopant and attaining more enhancement by using a plurality of dopants in combination, a technique capable of more improving the reciprocity failure over wide illuminance from low illuminance exposure for an exposure time of about 10 seconds to high illuminance exposure for about 10−6 second's (that is, a technique capable of achieving agreement of sensitivity in this range) without adversely affecting other performances such as sensitivity, gradation and latent image storability is being demanded.